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MSL Component - Popcorn Temp.

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#66745

MSL Component - Popcorn Temp. | 4 July, 2012

Assuming that you have a saturated moisture-sensitive component: At what temperature would popcorning or internal component damage occur? I would guess that it would be at a temperature where water would boil, around 100 degrees? However, the JEDEC J-STD-033A says that you can bake a component at 125 degrees to remove moisture, so this must be wrong?

I'm working on a populated PCB pre-baking procedure (for BGA rework). The purpose is to remove moisture from the PCB to prevent de-lamanation during reflow. A lot of questions have come up.

Some people have recommended 105-120 degrees, but if this is past the boiling point of water, wouldn't that cause component damage while trying to dry the PCB? Also, a lot of people have suggested using table 4-1 from JEDEC J-STD-033A. However, this standard applies to SMD packages, and not to populated PCB's. Either way, the allowed maximum temperature is 125 degrees.

So, does anyone know what maximum temperature can be safely applied to an MSL component while avoiding damage?

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#66750

MSL Component - Popcorn Temp. | 4 July, 2012

Baking boards to remove moisture takes a lot more energy than you'd think. Following on with this, Chris Hunt from NPL gave a presentation at IPC APEX 2012 about the results of his research ["Impedance Testing for Sensitivity to Delamination in Printed Circuit Boards" C.P. Hunt, M Wickham, O Thomas, L Zou, MAT 40, March 2010] on baking boards. It was: * Startling how long to took to bake boards * Amazing how ground planes affected the movement and concentration of moisture from the board during baking

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#66752

MSL Component - Popcorn Temp. | 4 July, 2012

Thanks for the reply. Do you know if there is an electronic copy of this presentation?

Thanks.

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#66753

MSL Component - Popcorn Temp. | 4 July, 2012

Look on the NPL site or just google the title

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